3.1: Biological Molecules

External Assessments:

AS – Paper 1 and Paper 2

A-level – Paper 1 and Paper 3

Required Practicals:

1. Investigation into the effect of a named variable on the rate of an enzyme-controlled reaction

Internal Assessments:

1. Carbohydrates and lipids exam questions (due: )

2. Proteins and enzymes exam questions (due: )

3. DNA and RNA exam questions (due: )

4. End of topic test

Comments:

3.1.1: Monomers and Polymers

What is polymerisation?

Monomers and Polymers

What is the difference between a monomer and a polymer?How does a condensation reaction take place?How does a hydrolysis reaction take place?During which process/group of processes are polymers hydrolysed in the body into monomers?

Keywords:Polymers, monomers, polymerisation, monosaccharaides, disaccharides, polysaccharides, soluble, insoluble, isomers, nucleotides, polynucleotide, amino acids, dipeptide, polypeptide, condensation, hydrolysis.

What are isomers? Draw a general structure of an amino acid, which is an example of a monomer.

Draw a diagram of the condensation and hydrolysis reactions between two α-glucose monomers.

3.1.2: Carbohydrates

Starch, glycogen and cellulose:How are α-glucose monomers arranged to form the polymers of starch and glycogen?How are β-glucose monomers arranged to form the polymer cellulose?How do the molecular structure of starch, glycogen and cellulose relate to their function?

Key words: starch; condensation reaction; osmosis; glycogen; cellulose; hydrogen bonds

Label the diagram to show the structure of starch:

List some of the properties of starch:

What is glycogen and what is it used for?

Draw a diagram to show the structure of cellulose:

Explain how its structure relates to its function:

3.1.3: Lipids

Triglycerides and Phospholipids

How are triglycerides formed?Are triglycerides polymers?How does the structure of a phospholipid differ from a triglyceride?

Keywords:

Triglycerides, Phospholipids, Saturated, Unsaturated, Hydrophobic, Hydrophilic, R-group, Emulsion test

Draw the basic structure of a triglyceride and label the parts.

Draw the basic structure of a phospholipid and label the parts.

What do the keywords below mean?

Hydrophilic:

Hydrophobic:

Which part of a phospholipid is hydrophilic and which is hydrophobic?

Describe the emulsion test, using diagrams.

Carbohydrates and Lipids Exam Questions (due: )

2. The diagram shows a triglyceride molecule.

(a) Name part A.……………………………………………………………….. (1)

(b) With reference to the named parts of the diagram, explain the difference between the terms:

(i) Triglyceride and phospholipid;

………………………………………………………………………………

……….......……………………………………………………….........(2)

(ii) saturated and unsaturated.

………………………………………………………………………………

……….......……………………………………………………….........(2)

H C O C

H C O C

H C O C

H

H

O

O

O

A

F a tty a c id 1

F a tty a c id 2

F a tty a c id 3

1. Name the monosaccharides of which the following disaccharides are composed.

(a) (i) Sucrose

Monosaccharides

………………………….and …………………………… (1)

(b) (ii) Lactose

Monosaccharides

………………………….and …………………………… (1)

(b) Describe how you would use a biochemical test to show that a

solution contained a non-reducing sugar, such as sucrose.

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

……………………………………………………………………………

........................................................................................................

................................................................................................. (3)

3.1.4.1: General Properties of Proteins

Label the diagram to show the formation of a polypeptide bond:

ProteinsHow are amino acids linked to for polypeptides – the primary structure of proteins?How are polypeptides arranged to form the secondary structure and then the tertiary structure of a protein?How is the quaternary structure of a protein formed?How are proteins identified?

Key words: alpha-helix; amino acid; β-pleated sheet; biuret test; dipeptide; disulphide bonds; ionic bonds; hydrogen bonds; peptide bond; polymerisation; polypeptide; primary structure; protein; quaternary structure; secondary structure; tertiary structure;

Draw and label an amino acid:

What is the test for proteins and what results would you expect?

3.1.4.1: General Properties of Proteins

Draw the tertiary structure of a protein:

ProteinsHow are amino acids linked to for polypeptides – the primary structure of proteins?How are polypeptides arranged to form the secondary structure and then the tertiary structure of a protein?How is the quaternary structure of a protein formed?How are proteins identified?

Key words: alpha-helix; amino acid; β-pleated sheet; biuret test; dipeptide; disulphide bonds; ionic bonds; hydrogen bonds; peptide bond; polymerisation; polypeptide; primary structure; protein; quaternary structure; secondary structure; tertiary structure;

Draw the primary structure of a protein:

Draw the secondary structure of a protein:

Draw the quaternary structure of a protein:

3.1.4.2: Enzymes

Enzyme actionHow do enzymes speed up chemical reactions?How does the structure of enzyme molecules relate to their function?What is the lock and key model of enzyme action?What is the induced-fit model of enzyme action?

Key words:activation energy; catalyst; enzyme; enzyme-substrate complex; induced fit; lock and key; substrate;

Draw a diagram to explain the lock and key model of enzyme action:

Draw a diagram to explain the induced-fit model of enzyme action:

How does an enzyme’s structure relate to its function?

Draw a sketch graph to show how enzymes speed up a reaction:

3.1.4.2: Enzymes

How does substrate concentration affect the rate of an enzyme-controlled reaction?

How does pH affect the rate of an enzyme-controlled reaction?

Factors affecting enzyme actionHow is the rate of an enzyme-controlled reaction measured?How does temperature affect the rate of an enzyme-controlled reaction?How does pH affect the rate of enzyme-controlled reaction?How does substrate concentration affect the rate of reaction?

Key words:active site; denature; optimum; pH; substrate concentration; temperature

How does temperature affect the rate of an enzyme-controlled reaction?

3.1.4.2: Enzymes

Enzyme inhibitionHow do competitive inhibitors and non-competitive inhibitors affect the active site?What is enzyme inhibition?

Key words:competitive inhibitor; end-product inhibitor; irreversible; reversible; non-competitive inhibitor

How do competitive inhibitors affect the active site? Use diagrams in your explanation.

How do non-competitive inhibitors affect the active site? Use diagrams in your explanation.

Proteins and Enzymes Exam Questions (due: )

1. A protein is formed from 300 amino acids. The diagrams show the primary, secondary and tertiary structures of this protein.

P rim ary s tru c tu re . L en g th = 3 0 0 n m

S ec o n d ary stru c tu re . L en g th = 4 5 n m

Te rtia ry s tru c tu re . L en g th = 8 .6 n m

(i) Explain what causes the secondary structure to differ in length from the primary structure.

…………………………………………………………………………

……………………………………………………………………….(1)

(ii) Explain what is meant by the tertiary structure of a protein.

…………………………………………………………………………

……………………………………………………………………….(1)

(iii) Heating may affect the tertiary structure of a protein. Explain how.

…………………………………………………………………………

…………………………………………………………………………

…………………………………………………………………………

……………………………………………………………………....(2)

P rim ary s tru c tu re . L en g th = 3 0 0 n m

S ec o n d ary stru c tu re . L en g th = 4 5 n m

Te rtia ry s tru c tu re . L en g th = 8 .6 n m

P rim ary s tru c tu re . L en g th = 3 0 0 n m

S ec o n d ary stru c tu re . L en g th = 4 5 n m

Te rtia ry s tru c tu re . L en g th = 8 .6 n m

2. The graph shows the effect of substrate concentration on the rate of an enzyme-controlled reaction.

(a) (i) Describe what the graph shows about the effect of substrate

concentration on the rate of this enzyme-controlled reaction.

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

…………………………………………………………………(2)a) (ii) What limits the rate of this reaction between points A and B?

Give the evidence from the graph for this.

………………………………………………………………………………

………………………………………………………………………………

………………………………………………………………………………

…………………………………………………………………(2)

3.1.5.1: Structure of DNA and RNA

Draw and label a nucleotide

Structure of DNAWhat are the components of DNA?How are these components arranged within the DNA double helix?What is the function of DNA?

Key words: cytosine; thymine; adenine; guanine; phosphate; deoxyribose sugar; condensation reaction; mononucleotide; dinucleotide; polynucleotide; complementary; double helix; antiparallel; hydrogen bonds

List the four bases under the following columns:

Explain how DNA forms a double helix using the key words above:

Explain how to the structure of DNA is linked to its function:1.

2.

3.

Draw and label how two nucleotides condense to form the start of a polynucleotide strand

Purines Pyrimidines

3.1.5.1: Structure of DNA and RNA

Structure of RNAWhat are the components of RNA?How and where is RNA used in cells?

How is the structure of RNA different from that of DNA?

Name and explain 3 types of RNA and how they are important:

Key words:adenine; thymine; guanine; cytosine; uracil; deoxyribose; ribose; rRNA; mRNA; tRNA

3.1.5.2: DNA Replication

Explain the semi conservative model of DNA replication using the key words above:

Replication of DNAWhat happens during DNA replication?How is a new polynucleotide strand formed?Why is the process of DNA replication called semi-conservation?

Key words:nuclear division; cell division; DNA helicase; DNA polymerase, hydrogen bonds, nucleotides, complementary

3.1.5.2: DNA Replication

Explain the experimental evidence for semi conservative replication of DNA using the diagram below.

Experimental Evidence for Semi-Conservative ReplicationWhat happens during DNA replication?How is a new polynucleotide strand formed?Why is the process of DNA replication called semi-conservation?

Key words:nuclear division; cell division; DNA helicase; DNA polymerase, hydrogen bonds, nucleotides, complementary

DNA and RNA Exam Questions (due: )

The diagram shows part of a DNA molecule.

DNA is a polymer. What is the evidence from the diagram that DNA is a polymer? (1)

Name the parts of the diagram labelled C, D and E.

Part C………………………………………….

Part D………………………………………….

Part E…………………………………… ...(3)

In a piece of DNA, 34% of the bases were thymine.Complete the table to show the name and percentages of the other bases. (2)

Name of base Percentage

Thymine 34

34

DNA and RNA Exam Questions (due: )

The diagram shows the bases in a rRNA molecule. In addition to A, U, C and G there are other bases present in tRNA. The other bases are shown by the letter D.

Which of the bases also occur in DNA? (1)

DNA and tRNA are both polynucleotide strands. Other than their nucleotide structure, give one similarity between the structures of DNA and tRNA (1)

Other than the difference in some of the bases, give three ways in which the structure of DNA is different from tRNA. (3)

1

2

3

DNA and RNA Exam Questions (due: )

Describe how DNA is replicated (6)

Total mark for DNA and RNA Exam Qs:

/17

3.1.6: ATP

ATPWhat are the components of ATP?How is ATP broken down?How is ATP formed?

Key words: adenosine triphosphate; adenine; ribose; inorganic phosphate; ATP hydrolase; hydrolysis; phosphorylate; condensation; respiration.

Label the diagram of an ATP molecule: Use a labelled diagram to explain the hydrolysis of ATP:

How is ATP resynthesised after hydrolysis?

3.1.7: Water

Water is a major component of cells. It has several properties that are important in biology

Keywords: metabolite; hydrogen bonding; dipolar; specific heat capacity; latent heat of vaporisation; cohesion; surface temperature

Explain the role of water, with examples,in terms of:

Role as a metabolite:

Role as a solvent:

Has a high specific heat capacity:

Large latent heat of vaporisation:

Strong cohesion between the molecules: